Electron-scattering studies of correlations in nuclei

The authors review theoretical estimates of spatial, spin, and isospin correlations among the nucleons in nuclei. The momentum distribution and spectral function of nucleons in nuclei are also discussed. The theoretical estimates are compared with the observed correlation effects in the inclusive scattering of electrons from nuclei, at energies ranging from a few hundred MeV to several GeV. The observed transparencies of nuclei to protons ejected in inclusive $e$,$e^{\prime }p$ reactions are also compared with their theoretical estimates. Finally, the quenching of exclusive single-quasiparticle-type reactions, indicative of the overall strength of correlations in nuclei, is discussed. There appears to be a qualitative agreement between theory and experiment, but a firm quantitative understanding is still to be obtained.